Adding DRP specfic UMA for FirstContentfulPaint

content/public/browser/navigation_data.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_
+#define CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_
+
+#include <memory>
+
+#include "base/macros.h"
+
+namespace content {
+
+// Copyable interface for embedders to pass opaque data to content.

[nasko, 2016/04/26 20:18:40]

Let's add also a bit about the contract of this data type. It is expected to be
set on the IO thread and content will transfer it over to the UI thread.

[RyanSturm, 2016/04/27 23:27:47]

Done.

+class NavigationData {
+ public:
+  virtual ~NavigationData(){};
+  // Creates a new NavigationData that is completely independent of the

[nasko, 2016/04/26 20:18:40]

nit: Empty line above the comment.

s/completely independent/deep copy/.

[RyanSturm, 2016/04/27 23:27:47]

Done.

+  // original, and could be used cross-thread.
+  virtual std::unique_ptr<NavigationData> Clone() const = 0;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_NAVIGATION_DATA_H_